1.1 Field of the Invention
This invention is in the fields of automobile safety, intelligent highway safety systems, accident avoidance, accident elimination, collision avoidance, blind spot detection, anticipatory sensing, automatic vehicle control, intelligent cruise control, vehicle navigation, vehicle to vehicle communication, vehicle to non-vehicle communication and non-vehicle to vehicle communication and other automobile, truck and train safety, navigation, communication and control related fields.
The invention relates generally to methods for vehicle-to-vehicle communication and communication between a vehicle and non-vehicles and more particularly to apparatus and methods using coded spread spectrum, ultrawideband, noise radar or similar technologies. The coding scheme can use may be implemented using multiple access communication methods analogous to frequency division multiple access (FDMA), timed division multiple access (TDMA), or code division multiple access (CDMA) in a manner to permit simultaneous communication with and between a multiplicity of vehicles but without the use of a carrier frequency.
The invention also relates generally to an apparatus and method for precisely determining the location and orientation of a host vehicle operating on a roadway and location of multiple moving or fixed obstacles that represent potential collision hazards with the host vehicle to thereby eliminate collisions with such hazards. In the early stages of implementation of the apparatus and method and when collisions with such hazards cannot be eliminated, the apparatus and method will generate warning signals and possibly initiate avoidance maneuvers to minimize the probability of a collision and the consequences thereof. More particularly, the invention relates to the use of a Global Positioning System (xe2x80x9cGPSxe2x80x9d), differential GPS (xe2x80x9cDGPSxe2x80x9d), other infrastructure-based location aids, cameras, radar and laser radar and an inertial navigation system as the primary host vehicle and target locating system with centimeter level accuracy. The invention is further supplemented by a digital computer system to detect, recognize and track all relevant potential obstacles, including other vehicles, pedestrians, animals, and other objects on or near the roadway. More particularly, the invention further relates to the use of centimeter-accurate maps for determining the location of the host vehicle and obstacles on or adjacent the roadway. Even more particularly, the invention further relates to an inter-vehicle and vehicle to infrastructure communication systems for transmitting GPS and DGPS position data, as well as, relevant target data to other vehicles for information and control action. The present invention still further relates to the use of neural networks and neural-fuzzy rule sets for recognizing and categorizing obstacles and generating and developing optimal avoidance maneuvers where necessary.
Automobile accidents are one of the most serious problems facing society today, both in terms of deaths and injuries, and in financial losses suffered as a result of accidents. The suffering caused by death or injury from such accidents is immense. The costs related to medical treatment, permanent injury to accident victims and the resulting loss of employment opportunities, and financial losses resulting from damage to property involved in such accidents are staggering. Providing the improved systems and methods to eventually eliminate these deaths, injuries and other losses deserves the highest priority. The increase in population and use of automobiles worldwide with the concomitant increased congestion on roadways makes development of systems for collision elimination even more urgent. While many advances have been made in vehicle safety, including, for example, the use of seatbelts, airbags and safer automobile structures, much room for improvement exists in automotive safety and accident prevention systems.
There are two major efforts underway that will significantly affect the design of automobiles and highways. The first is involved with preventing deaths and serious injuries from automobile accidents. The second involves the attempt to reduce the congestion on highways. In the first case, there are approximately forty two thousand (42,000) people killed each year in the United States by automobile accidents and another several hundred thousand are seriously injured. In the second case, hundreds of millions of man-hours are wasted every year by people stuck in traffic jams on the world""s roadways. There have been many attempts to solve both of these problems; however, no single solution has been able to do so.
When a person begins a trip using an automobile, he or she first enters the vehicle and begins to drive, first out of the parking space and then typically onto a local or city road and then onto a highway. In leaving the parking space, he or she may be at risk from an impact of a vehicle traveling on the road. The driver must check his or her mirrors to avoid such an event and several electronic sensing systems have been proposed which would warn the driver that a collision is possible. Once on the local road, the driver is at risk of being impacted from the front, side and rear, and electronic sensors are under development to warn the driver of such possibilities. Similarly, the driver may run into a pedestrian, bicyclist, deer or other movable object and various sensors are under development that will warn the driver of these potential events. These various sensors include radar, optical, infrared, ultrasonic, and a variety of other sensors, each of which attempts to solve a particular potential collision event. It is important to note that as yet, in none of these cases is there sufficient confidence in the decision that the control of the vehicle is taken away from the driver. Thus, action by the driver is still invariably required.
In some proposed future Intelligent Transportation System (ITS) designs, hardware of various types is embedded into the highway and sensors which sense this hardware are placed onto the vehicle so that it can be accurately guided along a lane of the highway. In various other systems, cameras are used to track lane markings or other visual images to keep the vehicle in its lane. However, for successful ITS, additional information is needed by the driver, or the vehicle control system, to take into account weather, road conditions, congestion etc., which typically involves additional electronic hardware located on or associated with the highway as well as the vehicle. From this discussion, it is obvious that a significant number of new electronic systems are planned for installation onto automobiles. However, to date, no product has been proposed or designed which combines all of the requirements into a single electronic system. This is one of the intents of some embodiments of this invention.
The safe operation of a vehicle can be viewed as a process in the engineering sense. To achieve safe operation, first the process must be designed and then a vehicle control system must be designed to implement the process. The goal of a process designer is to design the process so that it does not fail. The fact that so many people are being seriously injured and killed in traffic accidents and the fact that so much time is being wasted in traffic congestion is proof that the current process is not working and requires a major redesign. To design this new process, the information required by the process must be identified, the source of that information determined and the process designed so that the sources of information can communicate effectively with the user of the information, which will most often be a vehicle control system. Finally, the process must have feedback that self-corrects the process when it is tending toward failure.
Although it is technologically feasible, it is probably socially unacceptable at this time for a vehicle safety system to totally control the vehicle. An underlying premise of embodiments of this invention, therefore, is that people will continue to operate their vehicle and control of the vehicle will only be seized by the control system when such an action is required to avoid an accident or when such control is needed for the orderly movement of vehicles through potentially congested areas on a roadway. When this happens, the vehicle operator will be notified and given the choice of exiting the road at the next opportunity. In some implementations, especially when this invention is first implemented on a trail basis, control will not be taken away from the vehicle operator but a warning system will alert the driver of a potential collision, road departure or other infraction.
Let us consider several scenarios and what information is required for the vehicle control process to prevent accidents. In one case, a driver is proceeding down a country road and falls asleep and the vehicle begins to leave the road, perhaps heading toward a tree. In this case, the control system would need to know that the vehicle was about to leave the road and for that, it must know the position of the vehicle relative to the road. One method of accomplishing this would be to place a wire down the center of the road and to place sensors within the vehicle to sense the position of the wire relative to the vehicle, or vice versa. An alternate approach would be for the vehicle to know exactly where it is on the surface of the earth and to also know exactly where the edge of the road is.
These approaches are fundamentally different because in the former solution every road in the world would require the placement of appropriate hardware as well as the maintenance of this hardware. This is obviously impractical. In the second case, the use of the global positioning satellite system (GPS), augmented by additional systems to be described below, will provide the vehicle control system with an accurate knowledge of its location. While it would be difficult to install and maintain hardware such as a wire down the center of the road for every road in the world, it is not difficult to survey every road and record the location of the edges, and the lanes for that matter, of each road. This information must then be made available through one or more of a variety of techniques to the vehicle control system.
Another case might be where a driver is proceeding down a road and decides to change lines while another vehicle is in the driver""s blind spot. Various companies are developing radar, ultrasonic or optical sensors to warn the driver if the blind spot is occupied. The driver may or may not heed this warning, perhaps due to an excessive false alarm rate, or he or she may have become incapacitated, or the system may fail to detect a vehicle in the blind spot and thus the system will fail.
Consider an alternative technology where again each vehicle knows precisely where it is located on the earth surface and additionally can communicate this information to all other vehicles within a certain potential danger zone relative to the vehicle. Now, when the driver begins to change lanes, his or her vehicle control system knows that there is another vehicle in the blind spot and therefore will either warn the driver or else prevent him or her from changing lanes thereby avoiding the accident.
Similarly, if a vehicle is approaching a stop sign, other traffic marker or red traffic light and the operator fails to bring the vehicle to a stop, if the existence of this traffic light and its state (red in this example) or stop sign has been made available to the vehicle control system, the system can warn the driver or seize control of the vehicle to stop the vehicle and prevent a potential accident. Additionally, if an operator of the vehicle decides to proceed across an intersection without seeing an oncoming vehicle, the control system will once again know the existence and location and perhaps velocity of the oncoming vehicle and warn or prevent the operator from proceeding across the intersection.
Consider another example where water on the surface of a road is beginning to freeze. Probably the best way that a vehicle control system can know that the road is about to become slippery, and therefore that the maximum vehicle speed must be significantly reduced, is to get information from some external source. This source can be sensors located on the highway that are capable of determining this condition and transmitting it to the vehicle. Alternately, the probability of icing occurring can be determined analytically from meteorological data and a historical knowledge of the roadway and communicated to the vehicle over a LEO satellite system, the Internet or an FM sub-carrier or other means. A combination of these systems can also be used.
Studies have shown that a combination of meteorological and historic data can accurately predict that a particular place on the highway will become covered with ice. This information can be provided to properly equipped vehicles so that the vehicle knows to anticipate slippery roads. For those roads that are treated with salt to eliminate frozen areas, the meteorological and historical data will not be sufficient. Numerous systems are available today that permit properly equipped vehicles to measure the coefficient of friction between the vehicle""s tires and the road. It is contemplated that perhaps police or other public vehicles will be equipped with such a friction coefficient measuring apparatus and can serve as probes for those roadways that have been treated with salt. Information from these probe vehicles will be fed into the information system that will then be made available to control speed limits in the those areas.
Countless other examples exist; however, from those provided above it can be seen that for the vehicle control system to function without error, certain types of information must be accurately provided. These include information permitting the vehicle to determine its absolute location and means for vehicles near each other to communicate this location information to each other. Additionally, map information that accurately provides boundary and lane information of the road must be available. Also, critical weather or road-condition information is necessary. The road location information need only be generated once and changed whenever the road geometry is altered. This information can be provided to the vehicle through a variety of techniques including prerecorded media such as CD-ROM or DVD disks or through communications from transmitters located in proximity to the vehicle, satellites, radio and cellular phones.
Consider now the case of the congested highway. Many roads in the world are congested and are located in areas where the cost of new road construction is prohibitive or such construction is environmentally unacceptable. It has been reported that an accident on such a highway typically ties up traffic for a period of approximately four times the time period required to clear the accident. Thus, by eliminating accidents, a substantial improvement of the congested highway problem results. This of course is insufficient. On such highways, each vehicle travels with a different spacing, frequently at different speeds and in the wrong lanes. If the proper spacing of the vehicles could be maintained, and if the risk of an accident could be substantially eliminated, vehicles under automatic control could travel at substantially higher velocities and in a more densely packed configuration thereby substantially improving the flow rate of vehicles on the highway by as much as a factor of 3 to 4 times. This not only will reduce congestion but also improve air pollution. Once again, if each vehicle knows exactly where it is located, can communicate its location to surrounding vehicles and knows precisely where the road is located, then the control system in each vehicle has sufficient information to accomplish this goal.
Again, an intent of the system and process described here is to totally eliminate automobile accidents as well as reduce highway congestion. This process is to be designed to have no defective decisions. The process employs information from a variety of sources and utilizes that information to prevent accidents and to permit the maximum vehicle throughput on highways.
The information listed above is still insufficient. The geometry of a road or highway can be determined once and for all, until erosion or construction alters the road. Properly equipped vehicles can know their location and transmit that information to other properly equipped vehicles. There remains a variety of objects whose location is not fixed, which have no transmitters and which can cause accidents. These objects include broken down vehicles, animals such as deer which wander onto highways, pedestrians, bicycles, objects which fall off of trucks, and especially other vehicles which are not equipped with location determining systems and transmitters for transmitting that information to other vehicles. Part of this problem can be solved for congested highways by restricting access to these highways to vehicles that are properly equipped. Also, these highways are typically in urban areas and access by animals can be effectively eliminated. Heavy fines can be imposed on vehicles that drop objects onto the highway. Finally, since every vehicle and vehicle operator becomes part of the process, each such vehicle and operator becomes a potential source of information to help prevent catastrophic results. Thus, each vehicle should also be equipped with a system of essentially stopping the process in an emergency. Such a system could be triggered by vehicle sensors detecting a problem or by the operator strongly applying the brakes, rapidly turning the steering wheel or by activating a manual switch when the operator observes a critical situation but is not himself in immediate danger. An example of the latter case is where a driver witnesses a box falling off of a truck in an adjacent lane.
To solve the remaining problems, therefore, each vehicle should also be equipped with an anticipatory collision sensing system, or collision forecasting system, which is capable of identifying or predicting and reacting to a pending accident. As the number of vehicles equipped with the control system increases, the need for the collision forecasting system will diminish.
Once again, the operator will continue to control his vehicle provided he or she remains within certain constraints. These constraints are like a corridor. As long as the operator maintains his vehicle within this allowed corridor, he or she can operate that vehicle without interference from the control system. That corridor may include the entire width of the highway when no other vehicles are present or it may be restricted to all eastbound lanes, for example. In still other cases, that corridor may be restricted to a single line and additionally, the operator may be required to keep his vehicle within a certain spacing tolerance from the preceding vehicle. If a vehicle operator wishes to exit a congested highway, he could operate his turn signal that would inform the control system of this desire and permit the vehicle to safely exit from the highway. It can also inform other adjacent vehicles of the operator""s intent, which could then automatically cause those vehicles to provide space for lane changing, for example. The highway control system is thus a network of individual vehicle control systems rather than a single highway resident computer system.
1.1.1 U.S. Department of Transportation (DOT) policy
In the DOT FY 2000 Budget in Brief Secretary Rodney Slater states that xe2x80x9cHistoric levels of federal transportation investment . . . are proposed in the FY 2000 budget.xe2x80x9d Later, Secretary Slater states that xe2x80x9cTransportation safety is the number one priority.xe2x80x9d DOT has estimated that $165 billion per year are lost in fatalities and injuries on U.S. roadways. Another $50 billion are lost in wasted time of people on congested highways. Presented herein is a plan to eliminate fatalities and injuries and to substantially reduce congestion. The total cost of implementing this plan is minuscule compared to the numbers stated above. This plan has been named the xe2x80x9cRoad to Zero Fatalities(trademark)xe2x80x9d, or RtZF(trademark) for short.
In the DOT Performance Plan FY 2000, Strategic Goal: Safety, it is stated that xe2x80x9cThe FY 2000 budget process proposes over $3.4 billion for direct safety programs to meet this challenge.xe2x80x9d The challenge is to xe2x80x9cPromote the public health and safety by working toward the elimination of traffic related deaths, injuries and property damagexe2x80x9d. The goal of the RtZF(trademark) is the same and herein a plan is presented for accomplishing this goal. The remainder of the DOT discussion centers around wishful thinking to reduce the number of transportation related deaths, injuries, etc. However, the statistics presented show that in spite of this goal, the number of deaths is now increasing. As discussed below, this is the result of a failed process.
Reading through the remainder of the DOT Performance Plan FY 2000, one is impressed by the billions of dollars that are being spent to solve the highway safety problem coupled with the enormous improvement that has been made until the last few years. It can also be observed that the increase in benefits from these expenditures has now disappeared. For example, the fatality rate per 100 million vehicle miles traveled fell from 5.5 to 1.7 in the period from the mid-1960s to 1994. But this decrease has now substantially stopped! This is an example of the law of diminishing returns and signals the need to take a totally new approach to solving this problem.
1.1.2 U.S. Intelligent Vehicle Initiative (IVI) Policy
Significant funds have been spent on demonstrating various ITS technologies. It is now believed to be the time for implementation. With over 40,000 fatalities and almost four million people being injured every year on US roadways, it is certainly time to take affirmative action to stop this slaughter. The time for studies and demonstrations is past. However, the deployment of technologies that are inconsistent with the eventual solution of the problem will only delay implementation of the proper systems and thereby result in more deaths and injuries.
A primary goal of the Intelligent Vehicle Initiative was to reduce highway related fatalities per 100 million vehicle miles traveled from 1.7 in 1996 to 1.6 in 2000. Of course, the number of fatalities may still increase due to increased road use. If this reduction in fatalities comes about due to slower travel speeds, because of greater congestion, then has anything really been accomplished? Similar comments apply to the goal of reducing the rate of injury per 100 million vehicle miles from 141 in 1996 to 128 in 2000. An alternate goal is to have the technology implemented on all new vehicles by the year 2010 that will eventually eliminate all fatalities and injuries. As an intermediate milestone, it is proposed to have the technology implemented on all new vehicles by 2007 to reduce or eliminate fatalities caused by road departure, yellow line crossing, stop sign infraction, rear end and excessive speed accidents. Inventions described herein will explain how these are goals can be attained.
In the IVI Investment Strategy, Critical Technology Elements And Activities of the DOT, it says xe2x80x9cThe IVI will continue to expand these efforts particularly in areas such as human factors, sensor performance, modeling and driver acceptancexe2x80x9d. An alternate, more effective, concentration for investments would be to facilitate the deployment of those technologies that will reduce and eventually eliminate highway fatalities. Driver acceptance and human factors will be discussed below. Too much time and resources have already been devoted to these areas. Modeling can be extremely valuable and sensor performance is in a general sense a key to eliminating fatalities.
On Jul. 15, 1998, the IVI light vehicle steering committee met and recommended that the IVI program should be conducted as a government industry partnership like the PNGV. This is believed to be quite wrong and it is believed that the IVI should now move vigorously toward the deployment of proven technology.
The final recommendations of the committee was xe2x80x9cIn the next five years, the IVI program should be judged on addressing selected impediments preventing deployment, not on the effect of IVI services on accident rates.xe2x80x9d This is believed to be a mistake. The emphasis for the next five years should be to deploy proven technologies and to start down the Road to Zero Fatalities(trademark). Five years from now technology should be deployed on production vehicles sold to the public that have a significant effect toward reducing fatalities and injuries.
As described in the paper xe2x80x9cPreview Based Control of A Tractor Trailer Using DGPS For Preventing Road Departure Accidentsxe2x80x9d the basis of the technology proposed has been demonstrated.
1.2 Review of Relevant Prior Art
The complete disclosure of the following patents and publications is incorporated by reference herein in their entirety. Also, the systems disclosed in the patents may be used in the invention in appropriate part.
a. Vehicle Collision Warning and Control
The ALVINN project of Carnegie Mellon University (Jochem, Todd M., Pomerleau, Dean A., and Thorpe, Charles E., xe2x80x9cVision-Based Neural Network Road and Intersection Detection and Traversalxe2x80x9d, IEEE Conference on Intelligent Robots and Systems, Aug. 5-9, 1995, Pittsburgh, Pa., USA)) describes an autonomous land vehicle using a neural network. The neural network is trained based on how a driver drives the vehicle given the output from a video camera. The output of the neural network is the direction that the vehicle should head based on the input information from the video camera and the training based on what a good driver would do. Such a system can be used in some embodiments of the present invention to guide a vehicle to a safe stop in the event that the driver becomes incapacitated or some other emergency situation occurs wherein the driver is unable to control the vehicle. The input to the neural network in this case would be the map information rather than a video camera. Additionally, the laser radar imaging system of this invention could also be an input to the system. This neural network system can additionally take over in the event that an accident becomes inevitable. Simple neural networks are probably not sufficient for this purpose and neural fuzzy and modular neural networks are probably required.
U.S. Pat. No. 5,479,173 to Yoshioka, et al. uses a steering angle sensor, a yaw rate sensor and a velocity of the vehicle sensor to predict the path that the vehicle will take. It uses a radar unit to identify various obstacles that may be in the path of the vehicle, and it uses a CCD camera to try to determine that the road is changing direction in front of the vehicle. No mention is made of the accuracy with which these determinations are made. It is unlikely that sub-meter accuracy is achieved. If an obstacle is sensed, the brakes can be automatically activated.
U.S. Pat. No. 5,540,298 to Yoshioka, et al. is primarily concerned with changing the suspension and steering characteristics of the vehicle in order to prevent unstable behavior of the vehicle in response to the need to exercise a collision avoidance maneuver. The collision anticipation system consists of an ultrasonic unit and two optical laser radar units.
U.S. Pat. No. 5,572,428 to Ishida is concerned with using a radar system plus a yaw rate sensor and a velocity sensor to determine whether a vehicle will collide with another vehicle based on the area occupied by each vehicle. Naturally, since radar cannot accurately determine this area, it has to be assumed by the system.
U.S. Pat. No. 5,613,039 to Wang, et al. is a collision warning radar system utilizing a real time adaptive probabilistic neural network. Wang discloses that about 60% of roadway collisions could be avoided if the operator of the vehicle was provided warning at least one-half second prior to a collision. The radar system used by Wang consists of two separate frequencies. The reflective radar signals are analyzed by a probabilistic neural network that provides an output signal indicative of the likelihood and threat of a collision with a particular object. The invention further includes a Fourier transform circuit that converts the digitized reflective signal from a time series to a frequency representation. It is important to note that in this case, as in the others above, true collision avoidance will not occur since, without a knowledge of the roadway, two vehicles can be approaching each other on a collision course, each following a curved lane on a highway and yet the risk of collision is minimal due to the fact that each vehicle remains in its lane. Thus, true collision avoidance cannot be obtained without an accurate knowledge of the road geometry.
U.S. Pat. 5,983,161 to Lemelson describes a GPS-based collision avoidance and warning system that contains some of the features of embodiments of the present invention. This patent is primarily concerned with using centimeter-accuracy DGPS systems to permit vehicles on a roadway to learn and communicate their precise locations to other vehicles. In that manner, a pending collision can, in some cases, be predicted.
Lemelson does not use an inertial navigation system for controlling the vehicle between GPS updates. Thus, the vehicle can travel a significant distance before its position can be corrected. This can lead to significant errors. Lemelson also does not make use of accurate map database and thus it is unable to distinguish cases where two cars are on separate lanes but on an apparent collision course. Although various radar and lidar systems are generally disclosed, the concept of range gating is not considered. Thus, the Lemelson system is unable to provide the accuracy and reliability required by the Road to Zero Fatalities(trademark) system described herein.
b. Accurate Navigation
U.S. Pat. No. 5,504,482 to Schreder describes an automobile equipped with an inertial and satellite navigation system as well as a local area digitized street map. The main use of this patent is for route guidance in the presence of traffic jams, etc. Schreder describes how information as to the state of the traffic on a highway can be transmitted and utilized by a properly equipped vehicle to change the route the driver would take in going to his destination. Schreder does not disclose sub-meter vehicle location accuracy determination, nevertheless, this patent provides a good picture of the state of the art as can be seen from the following quoted paragraphs:
xe2x80x9c. . . there exists a wide range of technologies that have disadvantageously not been applied in a comprehensive integrated manner to significantly improve route guidance, reduce pollution, improve vehicular control and increase safety associated with the common automobile experience. For example, it is known that gyro based inertial navigation systems have been used to generate three-dimensional position information, including exceedingly accurate acceleration and velocity information over a relatively short travel distance, and that GPS satellite positioning systems can provide three-dimensional vehicular positioning and epoch timing, with the inertial system being activated when satellite antenna reception is blocked during xe2x80x9cdrop outxe2x80x9d for continuous precise positioning. It is also known that digitized terrain maps can be electronically correlated to current vehicular transient positions, as have been applied to military styled transports and weapons. For another example, it is also known that digitally encoded information is well suited to RF radio transmission within specific transmission carrier bands, and that automobiles have been adapted to received AM radio, FM radio, and cellular telecommunication RF transmissions. For yet another example, it is further known that automobile electronic processing has been adapted to automatically control braking, steering, suspension and engine operation, for example, anti-lock braking, four-wheel directional steering, dynamic suspension stiffening during turns and at high speeds, engine governors limiting vehicular speed, and cruise control for maintaining a desired velocity. For still another example, traffic monitors, such as road embedded magnetic traffic light sensor loops and road surface traffic flow meters have been used to detect traffic flow conditions. While these sensors, meters, elements, systems and controls have served limited specific purposes, the prior art has disadvantageously failed to integrate them in a comprehensive fashion to provide a complete dynamic route guidance, dynamic vehicular control, and safety improvement system.xe2x80x9d
xe2x80x9cRecently, certain experimental integrated vehicular dynamic guidance systems have been proposed. Motorola has disclosed an Intelligent Vehicle Highway System in block diagram form in copyright dated 1993 brochure. Delco Electronics has disclosed another Intelligent Vehicle Highway System also in block diagram form in Automotive News published on Apr. 12, 1993. These systems use compass technology for vehicular positioning. However, displacement wheel sensors are plagued by tire slippage, tire wear and are relatively inaccurate requiring recalibration of the current position. Compasses are inexpensive, but suffer from drifting particularly when driving on a straight road for extended periods. Compasses can sense turns, and the system may then be automatically recalibrated to the current position based upon sensing a turn and correlating that turn to the nearest turn on a digitized map, but such recalibration, is still prone to errors during excessive drifts. Moreover, digitized map systems with the compass and wheel sensor positioning methods operate in two dimensions on a three dimensional road terrain injecting further errors between the digitized map position and the current vehicular position due to a failure to sense the distance traveled in the vertical dimension.xe2x80x9d
xe2x80x9cThese Intelligent Vehicle Highway Systems appear to use GPS satellite reception to enhance vehicular tracking on digitized road maps as part of a guidance and control system. These systems use GPS to determine when drift errors become excessive and to indicate that recalibration is necessary. However, the GPS reception is not used for automatic accurate recalibration of current vehicular positioning, even though C-MIGITS and like devices have been used for GPS positioning, inertial sensing and epoch time monitoring, which can provide accurate continuous positioning.xe2x80x9d
xe2x80x9cThese Intelligent Vehicle Highway Systems use the compass and wheel sensors for vehicular positioning for route guidance, but do not use accurate GPS and inertial route navigation and guidance and do not use inertial measuring units for dynamic vehicular control. Even though dynamic electronic vehicular control, for example, anti-lock braking, anti-skid steering, and electronic control suspension have been contemplated by others, these systems do not appear to functionally integrate these dynamic controls with an accurate inertial route guidance system having an inertial measuring unit well suited for dynamic motion sensing. There exists a need to further integrate and improve these guidance systems with dynamic vehicular control and with improved navigation in a more comprehensive system.xe2x80x9d
xe2x80x9cThese Intelligent Vehicle Highway Systems also use RF receivers to receive dynamic road condition information for dynamic route guidance, and contemplate infrastructure traffic monitoring, for example, a network for road magnetic sensing loops, and contemplate the RF broadcasting of dynamic traffic conditions for dynamic route guidance. The disclosed two-way RF communication through the use of a transceiver suggests a dedicated two-way RF radio data system. While two-way RF communication is possible, the flow of necessary information between the vehicles and central system appears to be exceedingly lopsided. The flow of information from the vehicles to a central traffic radio data control system may be far less than the required information from traffic radio data control system to the vehicles. It seems that the amount of broadcasted dynamic traffic flow information to the vehicles would be far greater than the information transmitted from the vehicles to the central traffic control center. For example, road side incident or accident emergency messages to a central system may occur far less than the occurrences of congested traffic points on a digitized map having a large number of road coordinate points.xe2x80x9d
xe2x80x9cConserving bandwidth capacity is an objective of RF communication systems. The utilization of existing infra structure telecommunications would seem cost-effective. ATandT has recently suggested improving the existing cellular communication network with high-speed digital cellular communication capabilities. This would enable the use of cellular telecommunications for the purpose of transmitting digital information encoding the location of vehicular incidents and accidents. It then appears that a vehicular radio data system would be cost-effectively used for unidirectional broadcasting of traffic congestion information to the general traveling public, while using existing cellular telecommunication systems for transmitting emergency information. The communication system should be adapted for the expected volume of information. The Intelligent Vehicular Highway Systems disadvantageously suggest a required two-way RF radio data system. The vast amount of information that can be transmitted may tend to expand and completely occupy a dedicated frequency bandwidth. To the extent that any system is bi-directional in operation tends to disadvantageously require additional frequency bandwidth capacity and system complexity.xe2x80x9d
c. Vehicle Location
Several attempts to improve the position accuracy of GPS are discussed here, for example, the Wide Area Augmentation System (WAAS), the Local Area Augmentation System (LAAS) and various systems that make use of the carrier phase.
A paper by S. Malys et al., titled xe2x80x9cThe GPS Accuracy Improvement Initiativexe2x80x9d provides a good discussion of the errors inherent in the GPS system without using differential corrections. It is there reported that the standard GPS provides a 9-meter RMS 3-D navigational accuracy to authorize precise positioning service users. This reference indicates that there are improvements planned in the GPS system that will further enhance its accuracy. The accuracies of these satellites independently of the accuracies of receiving units is expected to be between 1 and 1.5 meters RMS. Over the past eight years of GPS operations, a 50% (4.6 meter to 2.3 meter) performance improvement has been observed for the signal in space range errors. This, of course, is the RMS error. The enhancements contained in the accuracy improvement initiative will provide another incremental improvement from the current 2.3 meters to 1.3 meters and perhaps to as low as 40 centimeters.
Pullen, Samuel, Enge, Per and Parkinson, Bradford, xe2x80x9cSimulation-Based Evaluation of WAAS Performance: Risk and Integrity Factorsxe2x80x9d discusses the accuracy that can be expected from the WAAS system. This paper indicates that the standard deviation for WAAS is approximately 1 meter. To get more accurate results requires more closely spaced differential stations. Using DGPS stations within 1,500 kilometers from the vehicle, high accuracy receivers can determine a location within 3 meters accuracy for DGPS according to the paper. Other providers of DGPS corrections claim considerably better accuracies.
From a paper by J. F. Zumberge, M. M. Watkins and F. H. Webb, titled xe2x80x9cCharacteristics and Applications of Precise GPS Clock Solutions Every 30 Secondsxe2x80x9d, Journal of the Institute of Navigation, Vol. 44, No. 4, Winter 1997-1998, it appears that by using the techniques described in this reference, the WAAS system could eventually be improved to provide accuracies in the sub-decimeter range for moving vehicles without the need for other DGPS systems. This data would be provided every 30 seconds.
W. I. Bertiger et al., xe2x80x9cA Real-Time Wide Area Differential GPS Systemxe2x80x9d, Journal of the Institute of Navigation, Vol. 44, No. 4, Winter 1997-1998. This paper describes the software that is to be used with the WAAS System. The WAAS System is to be completed by 2001. The goal of the research described in this paper is to achieve sub-decimeter accuracies worldwide, effectively equaling local area DGPS performance worldwide. The full computation done on a Windows NT computer adds only about 3 milliseconds. The positioning accuracy is approximately 25 centimeters in the horizontal direction. That is, the RMS value so that gives an error at xc2x13 sigma of 1.5 meters. Thus, this real time wide area differential GPS system is not sufficiently accurate for the purposes of some embodiments of this invention. Other systems claim higher accuracies.
According to the paper by R. Braff, titled xe2x80x9cDescription of the FAA""s Local Area Augmentation System (LAAS)xe2x80x9d, Journal of the Institute of Navigation, Vol. 44, No. 4, Winter 1997-1998, the LAAS System is the FAA""s ground-based augmentation system for local area differential GPS. It is based on providing corrections of errors that are common to both ground-based and aircraft receivers. These corrections are transmitted to the user receivers via very high frequency (VHF), line of sight radio broadcast. LAAS has the capability of providing accuracy on the order of 1 meter or better on the final approach segment and through rollout. LAAS broadcasts navigational information in a localized service volume within approximately 30 nautical miles of the LAAS ground segment.
O""Connor, Michael, Bell, Thomas, Elkaim, Gabriel and Parkinson, Bradford, xe2x80x9cAutomatic Steering of Farm Vehicles Using GPSxe2x80x9d describes an automatic steering system for farm vehicles where the vehicle lateral position error never deviated by more than 10 centimeters, using a carrier phase differential GPS system whereby the differential station was nearby.
The following quote is from Y. M. Al-Haifi et al., xe2x80x9cPerformance Evaluation of GPS Single-Epoch On-the Fly Ambiguity Resolutionxe2x80x9d, Journal of the Institute of Navigation, Vol. 44, No. 4, Winter 1997-1998. This technique demonstrates sub-centimeter precision results all of the time provided that at least five satellites are available and multipath errors are small. A resolution of 0.001 cycles is not at all unusual for geodetic GPS receivers. This leads to a resolution on the order of 0.2 millimeters. In practice, multipath affects, usually from nearby surfaces, limit the accuracy achievable to around 5 millimeters. It is currently the case that the reference receiver can be located within a few kilometers of the mobile receiver. In this case, most of the other GPS error sources are common. The only major problem, which needs to be solved to carry out high precision kinematic GPS, is the integer ambiguity problem. This is because at any given instant, the whole number of cycles between the satellite and the receiver is unknown. The recovery of the unknown whole wavelengths or integer ambiguities is therefore of great importance to precise phase positioning. Recently, a large amount of research has focused on so called on the fly (OTF) ambiguity resolution methodologies in which the integer ambiguities are solved for while the unknown receiver is in motion.xe2x80x9d
The half-second processing time required for this paper represents 44 feet of motion for a vehicle traveling at 60 mph, which would be intolerable unless supplemented by an inertial navigation system. The basic guidance system in this case would have to be the laser or MEMS gyro on the vehicle. With a faster PC, one-tenth a second processing time would be achievable, corresponding to approximately 10 feet of motion of the vehicle, putting less reliance on the laser gyroscope. Nowhere in this paper is the use of this system on automobiles suggested. The technique presented in this paper is a single epoch basis (OTF) ambiguity resolution procedure that is insensitive to cycle slips. This system requires the use of five or more satellites which suggests that additional GPS satellites may need to be launched to make the smart highway system more accurate.
F. van Diggelen, xe2x80x9cGPS and GPS+GLONASS RTKxe2x80x9d, ION-GPS, September 1997 xe2x80x9cNew Products Descriptionsxe2x80x9d, gives a good background of real time kinematic systems using the carrier frequency. The products described in this paper illustrate the availability of centimeter level accuracies for the purposes of the RtZF system. The product described in F. van Diggelen requires a base station that is no further than 20 kilometers away.
A paper by J. Wu and S. G. Lin, titled xe2x80x9cKinematic Positioning with GPS Carrier Phases by Two Types of Wide Laningxe2x80x9d, Journal of the Institute of Navigation, Vol. 44, No. 4, Winter 1997 discloses that the solution of the integer ambiguity problem can be simplified by performing other constructs other than the difference between the two phases. One example is to use three times one phase angle, subtracted from four times another phase angle. This gives a wavelength of 162.8 centimeters vs. 86.2 for the single difference. Preliminary results with a 20-kilometer base line show a success rate as high as 95% for centimeter level accuracies.
A paper by R. C. Hayward et al., titled xe2x80x9cInertially Aided GPS Based Attitude Heading Reference System (AHRS) for General Aviation Aircraftxe2x80x9d provides the list of inertial sensors that can be used with the teachings of embodiments of this invention.
K. Ghassemi et al., xe2x80x9cPerformance Projections of GPS IIFxe2x80x9d, describes the performance objectives for a new class of GPS 2F satellites scheduled to be launched in late 2001.
Significant additional improvement can be obtained for the WAAS system using the techniques described in the paper xe2x80x9cIncorporation of orbital dynamics to improve wide-area differential GPSxe2x80x9d by J. Ceva, W. Bertinger, R. Mullerschoen, T. Yunck and B. Parkinson, Institute on Navigation, Meeting on GPS Technology, Palm Springs, Calif., September 1995, which is incorporated herein by reference.
Singh, Daljit and Grewal, Harkirat, xe2x80x9cAutonomous Vehicle using WADGPSxe2x80x9d, discusses ground vehicle automation using wide-area DGPS. Though this reference describes many of the features of embodiments of the present invention, it does not disclose sub-meter accuracy or sub-meter accurate mapping.
U.S. Pat. No. 5,272,483 to Kato describes an automobile navigation system. This system attempts to correct for the inaccuracies in the GPS system through the use of an inertial guidance, geomagnetic sensor, or vehicle crank shaft speed sensor. However, it is unclear as to whether the second position system is actually more accurate than the GPS system. This combined system, however, cannot be used for sub-meter positioning of an automobile.
U.S. Pat. No. 5,383,127 to Shibata uses map matching algorithms to correct for errors in the GPS navigational system to provide a more accurate indication of where the vehicle is or, in particular, on what road the vehicle is. This procedure does not give sub-meter accuracy. Its main purpose is for navigation and, in particular, in determining the road on which the vehicle is traveling.
U.S. Pat. No. 5,416,712 to Geier, et al. relates generally to navigation systems and more specifically to global positioning systems that use dead reckoning apparatus to fill in as backup during periods of GPS shadowing such as occur amongst obstacles, e.g., tall buildings in large cities. This patent shows a method of optimally combining the information available from GPS even when less than 3 or 4 satellites are available with information from a low-cost, inertial gyro, having errors that range from 1-5%. This patent provides an excellent analysis of how to use a modified Kalman filter to optimally use the available information.
U.S. Pat. No. 5,606,506 to Kyrtsos provides a good background of the GPS satellite system. It describes a method for improving the accuracy of the GPS system using an inertial guidance system. This is based on the fact that the GPS signals used by Kyrtsos do not contain a differential correction and the selective access feature is on. Key paragraphs from this application that describe subject matter applicable to embodiments of the instant invention follow.
xe2x80x9cSeveral national governments, including the United States (U.S.) of America, are presently developing a terrestrial position determination system, referred to generically as a global positioning system (GPS). A GPS is a satellite-based radio-navigation system that is intended to provide highly accurate three-dimensional position information to receivers at or near the surface of the Earth.
xe2x80x9cThe U.S. government has designated its GPS the xe2x80x9cNAVSTAR.xe2x80x9d The NAVSTAR GPS is expected to be declared fully operational by the U.S. government in 1993. The government of the former Union of Soviet Socialist Republics (USSR) is engaged in the development of a GPS known as xe2x80x9cGLONASSxe2x80x9d. Further, two European systems known as xe2x80x9cNAVSATxe2x80x9d and xe2x80x9cGRANASxe2x80x9d are also under development. For ease of discussion, the following disclosure focuses specifically on the NAVSTAR GPS. The invention, however, has equal applicability to other global positioning systems.
xe2x80x9cIn the NAVSTAR GPS, it is envisioned that four orbiting GPS satellites will exist in each of six separate circular orbits to yield a total of twenty-four GPS satellites. Of these, twenty-one will be operational and three will serve as spares. The satellite orbits will be neither polar nor equatorial but will lie in mutually orthogonal inclined planes.xe2x80x9d
xe2x80x9cEach GPS satellite will orbit the Earth approximately once every 12 hours. This coupled with the fact that the Earth rotates on its axis once every twenty-four hours causes each satellite to complete exactly two orbits while the Earth turns one revolution.xe2x80x9d
xe2x80x9cThe position of each satellite at any given time will be precisely known and will be continuously transmitted to the Earth. This position information, which indicates the position of the satellite in space with respect to time (GPS time), is known as ephemeris data.xe2x80x9d
xe2x80x9cIn addition to the ephemeris data, the navigation signal transmitted by each satellite includes a precise time at which the signal was transmitted. The distance or range from a receiver to each satellite may be determined using this time of transmission which is included in each navigation signal. By noting the time at which the signal was received at the receiver, a propagation time delay can be calculated. This time delay when multiplied by the speed of propagation of the signal will yield a xe2x80x9cpseudorangexe2x80x9d from the transmitting satellite to the receiver.xe2x80x9d
xe2x80x9cThe range is called a xe2x80x9cpseudorangexe2x80x9d because the receiver clock may not be precisely synchronized to GPS time and because propagation through the atmosphere introduces delays into the navigation signal propagation times. These result, respectively, in a clock bias (error) and an atmospheric bias (error). Clock biases may be as large as several milliseconds.xe2x80x9d
xe2x80x9cUsing these two pieces of information (the ephemeris data and the pseudorange) from at least three satellites, the position of a receiver with respect to the center of the Earth can be determined using passive triangulation techniques.xe2x80x9d
xe2x80x9cTriangulation involves three steps. First, the position of at least three satellites in xe2x80x9cviewxe2x80x9d of the receiver must be determined. Second, the distance from the receiver to each satellite must be determined. Finally, the information from the first two steps is used to geometrically determine the position of the receiver with respect to the center of the Earth.xe2x80x9d
xe2x80x9cTriangulation, using at least three of the orbiting GPS satellites, allows the absolute terrestrial position (longitude, latitude, and altitude with respect to the Earth""s center) of any Earth receiver to be computed via simple geometric theory. The accuracy of the position estimate depends in part on the number of orbiting GPS satellites that are sampled. Using more GPS satellites in the computation can increase the accuracy of the terrestrial position estimate.xe2x80x9d
xe2x80x9cConventionally, four GPS satellites are sampled to determine each terrestrial position estimate. Three of the satellites are used for triangulation, and a fourth is added to correct for the clock bias described above. If the receiver""s clock were precisely synchronized with that of the GPS satellites, then this fourth satellite would not be necessary. However, precise (e.g., atomic) clocks are expensive and are, therefore, not suitable for all applications.xe2x80x9d
xe2x80x9cFor a more detailed discussion on the NAVSTAR GPS, see Parkinson, Bradford W. and Gilbert, Stephen W., xe2x80x9cNAVSTAR: Global Positioning Systemxe2x80x94Ten Years Later,xe2x80x9d Proceedings of the IEEE, Vol. 71, No. 10, October 1983; and GPS: A Guide to the Next Utility, published by Trimble Navigation Ltd., Sunnyvale, Calif., 1989, pp. 147, both of which are incorporated herein by reference. For a detailed discussion of a vehicle positioning/navigation system which uses the NAVSTAR GPS, see commonly owned U.S. patent application Ser. No. 07/628,560, entitled xe2x80x9cVehicle Position Determination System and Method,xe2x80x9d filed Dec. 3, 1990, which is incorporated herein by reference.xe2x80x9d
xe2x80x9cThe NAVSTAR GPS envisions two modes of modulation for the carrier wave using pseudorandom signals. In the first mode, the carrier is modulated by a xe2x80x9cC/A signalxe2x80x9d and is referred to as the xe2x80x9cCoarse/Acquisition modexe2x80x9d. The Coarse/Acquisition or C/A mode is also known as the xe2x80x9cStandard Positioning Servicexe2x80x9d. The second mode of modulation in the NAVSTAR GPS is commonly referred to as the xe2x80x9cprecisexe2x80x9d or xe2x80x9cprotectedxe2x80x9d (P) mode. The P-mode is also known as the xe2x80x9cPrecise Positioning Servicexe2x80x9d.
The P-mode is intended for use only by Earth receivers specifically authorized by the United States government. Therefore, the P-mode sequences are held in secrecy and are not made publicly available. This forces most GPS users to rely solely on the data provided via the C/A mode of modulation (which results in a less accurate positioning system)
xe2x80x9cIn addition to the clock error and atmospheric error, other errors which affect GPS position computations include receiver noise, signal reflections, shading, and satellite path shifting (e.g., satellite wobble). These errors result in computation of incorrect pseudoranges and incorrect satellite positions. Incorrect pseudoranges and incorrect satellite positions, in turn, lead to a reduction in the precision of the position estimates computed by a vehicle positioning system.xe2x80x9d
U.S. Pat. No. 5,757,646 to Talbot, et al. illustrates the manner in which centimeter level accuracy on the fly in real time is obtained. It is accomplished by double differencing the code and carrier measurements from a pair of fixed and roving GPS receivers. This patent also presents an excellent discussion of the problem and various prior solutions as in the following paragraphs:
xe2x80x9cWhen originally conceived, the global positioning system (GPS) that was made operational by the United States Government was not foreseen as being able to provide centimeter-level position accuracies. Such accuracies are now commonplace.xe2x80x9d
xe2x80x9cExtremely accurate GPS receivers depend on phase measurements of the radio carriers that they receive from various orbiting GPS satellites. Less accurate GPS receivers simply develop the pseudoranges to each visible satellite based on the time codes being sent. Within the granularity of a single time code, the carrier phase can be measured and used to compute range distance as a multiple of the fundamental carrier wavelength. GPS signal transmissions are on two synchronous, but separate carrier frequencies xe2x80x9cL1xe2x80x9d and xe2x80x9cL2xe2x80x9d, with wavelengths of nineteen and twenty-four centimeters, respectively. Thus, within nineteen or twenty-four centimeters, the phase of the GPS carrier signal will change 360xc2x0.xe2x80x9d
xe2x80x9cHowever the numbers of whole cycle (360xc2x0) carrier phase shifts between a particular GPS satellite and the GPS receiver must be resolved. At the receiver, every cycle will appear the same. Therefore there is an xe2x80x9cinteger ambiguityxe2x80x9d. The computational resolution of the integer ambiguity has traditionally been an intensive arithmetic problem for the computers used to implement GPS receivers. The traditional approaches to such integer ambiguity resolution have prevented on-the-fly solution measurement updates for moving GPS receivers with centimeter accurate outputs. Very often such highly accurate GPS receivers have required long periods of motionlessness to produce a first and subsequent position fix.xe2x80x9d
xe2x80x9cThere are numerous prior art methods for resolving integer ambiguities. These include integer searches, multiple antennas, multiple GPS observables, motion-based approaches, and external aiding. Search techniques often require significant computation time and are vulnerable to erroneous solutions when only a few satellites are visible. More antennas can improve reliability considerably. If carried to an extreme, a phased array of antennas results whereby the integers are completely unambiguous and searching is unnecessary. But for economy the minimum number of antennas required to quickly and unambiguously resolve the integers, even in the presence of noise, is preferred.xe2x80x9d
xe2x80x9cOne method for integer resolution is to make use of the other observables that modulate a GPS timer. The pseudo-random code can be used as a coarse indicator of differential range, although it is very susceptible to multipath problems. Differentiating the L1 and L2 carriers provides a longer effective wavelength, and reduces the search space. However dual frequency receivers are expensive because they are more complicated. Motion-based integer resolution methods make use of additional information provided by platform or satellite motion. But such motion may not always be present when it is needed.xe2x80x9d
This system is used in an industrial environment where the four antennas are relatively close to each other. Practicing teachings of this invention permits a navigational computer to solve for the position of the rover to within a few centimeters on the fly ten times a second. An example is given where the rover is an airplane.
The above comments related to the use of multiple antennas to eliminate the integer ambiguity suggest that if a number of vehicles are nearby and their relative positions are known, the ambiguity can be resolved.
d. Mapping
It is intended that the map database of embodiments of the instant invention will conform to the open GIS specification. This will permit such devices to additionally obtain on-line consumer information services such as driving advisories, digital yellow pages that give directions, local weather pictures and forecasts and video displays of local terrain since such information will also be in the GIS database format.
A paper by O""Shea, Michael and Shuman, Valerie entitled xe2x80x9cLooking Ahead: Map Databases in Predictive Positioning And Safety Systemsxe2x80x9d discusses map databases which can assist radar and image-processing systems of this invention since the equipped vehicle would know where the road ahead is and can therefore distinguish the lane of the preceding vehicle. No mention, however, is made in this reference of how this is accomplished through range gating or other means. This reference also mentions that within five years it may be possible to provide real time vehicle location information of one-meter accuracy. However, it mentions that this will be limited to controlled access roads such as interstate highways. In other words, the general use of this information on all kinds of roads for safety purposes is not contemplated. This reference also states that xe2x80x9croad geometry, for example, may have to be accurate to within one meter or less as compared to the best available accuracy of 15 meters todayxe2x80x9d. This reference also mentions the information about lane configuration that can be part of the database including the width of each lane, the number of lanes, etc., and that this can be used to determine driver drowsiness. This reference also states that xe2x80x9cat normal vehicle speeds, the vehicle location must be updated every few millisecondsxe2x80x9d. It is also stated that the combination of radar and map data can also help to interpret radar information such as the situation where a radar system describes an overpass as a semi truck. Image processing in this reference is limited to assessing road conditions such as rain, snow, etc. The use of a laser radar system is not contemplated by this reference. The use of this information for road departures warnings is also mentioned, as is lane following. The reference also mentions that feedback from vehicles can be used to improve map configurations.
A great flow of commercially available data will begin with the new generation of high resolution (as fine as about 1 meter) commercial earth imaging satellites from companies like EarthWatch and SPOT Image. Sophisticated imaging software is being put in place to automatically process these imaging streams into useful data products. This data can be used to check for gross errors in the map database.
According to Al Gore, in xe2x80x9cThe Digital Earth: Understanding our Planet in the 21st Centuryxe2x80x9d, California Science Center, Jan. 31, 1998, the Clinton Administration licensed commercial satellites to provide one meter resolution imaging beginning in 1998. Such imaging can be combined with digital highway maps to provide an accuracy and reality check.
U.S. Pat. No. 5,367,463 to Tsuji describes a vehicle azimuth determining system. It uses regression lines to find the vehicle on a map when there are errors in the GPS and map data. This patent does not give sub-meter accuracy. The advantage of this invention is that it shows a method of combining both map matching data and GPS along with a gyro and vehicle velocity and odometer data to improve the overall location accuracy of the vehicle.
e. Speed Control
U.S. Pat. No. 5,530,651 to Uemura, et al. describes a combination of an ultrasonic and laser radar optical detection system which has the ability to detect soiled lenses, rain, snow, etc. The vehicle control system then automatically limits the speed, for example, that the vehicle can travel in adverse weather conditions. The speed of the vehicle is also reduced when the visibility ahead is reduced due to a blind, curved corner. The permitted speed is thus controlled based on weather conditions and road geometry. There is no information in the vehicle system as to the legal speed limit as provided for in embodiments of the instant invention.
f. Precise Positioning
When the operator begins operating his vehicle with a version of the RtZF(trademark) system of this invention, he or she will probably not be near a reference point as determined by one of the radar reflector, MIR or RFID locator systems, for example. In this situation, he or she will use the standard GPS system with the WAAS or other DGPS corrections such as available from OmniStar(trademark), the US Government or other provider. This will provide accuracy of between a few meters to 6 centimeters. This accuracy might be further improved as he or she travels down the road through map-matching or through communication with other vehicles. The vehicle will know, however, that is not operating in the high accuracy mode. As soon as the vehicle (vehicle #1) passes a radar reflector, SAW, MIR, RFID or equivalent precise positioning system, it will be able to calculate exactly where it is within a few centimeters and the vehicle will know that it is in the accurate mode. Similarly, when another vehicle passes through a precise positioning station and learns its precise location it can communicate this fact with other vehicles in its vicinity (5 miles, for example) along with the latest GPS satellite transmissions. Each other vehicle will then be able to calculate its relative location extremely accurately and thus know its position almost as accurately as the vehicle that just passed through the precise positioning station. Furthermore, if vehicle #1 also has an accurate clock, as further described below, it can record the phase of each carrier wave from each satellite and predict that phase for perhaps an hour into the future. This then permits vehicle #1 to switch to carrier phase DGPS and know its precise position relative to the precise positioning station, and thus on the earth, until the clock accuracy degrades its knowledge of the carrier phase at the precise positioning station. Through continuous communication between vehicle #1 and other vehicles, all vehicles in the vicinity can similarly operate in the carrier phase DGPS mode without the need for the installation and maintenance of local DGPS stations. Thus, the addition of a few precise positioning stations at very low cost permits the each vehicle traveling on the road to know its precise location on the earth and for the system to approach perfection, a necessary requirement for achieving zero fatalities. For high-speed travel on a controlled highway, frequent precise positioning stations can be inexpensively provided and each vehicle can thereby be accurately contained within its proper corridor. Also, the size of the corridors that the vehicle is permitted to travel in can be a function of the accuracy state of the vehicle.
A paper by Han, Shaowei entitled xe2x80x9cAmbiguity Recovery For Long-Range GPS Kinematic Positioningxe2x80x9d appears to say that if a mobile receiver is initially synchronized with a fixed receiver such that there is no integer ambiguity, and if the mobile receiver then travels away from the fixed receiver, and during the process it loses contact with the satellites for a period of up to five minutes, that the carrier phase can be recovered and the ambiguity eliminated, providing again centimeter-range accuracies. Presumably, the fixed station is providing the differential corrections. This is important for embodiments of the instant invention since the integer ambiguity can be eliminated each time the vehicle passes a Precise Positioning Station (PPS) as explained below. After that, a five-minute loss of GPS signals should never occur. Thus, carrier phase accuracies will eventually be available to all vehicles. Note that the integer ambiguity problem disappears when the GPS satellites provide more frequencies. If, for example, each satellite would broadcast two frequencies with each frequency being a prime number of cycles per second, there would be no integer ambiguity problem. Due to the problem of identifying large prime numbers, other schemes can be used such that the relative phase of one carrier to the other does not repeat in the space from the vehicle to the satellite or if it does repeat, it repeats only a few times. This problem becomes simpler as more frequencies are added as for three frequencies, for example, the phase relation between any two can repeat as long as the phase relationships between all three don""t repeat very often.
For the purposes herein, a Precise Positioning Station, or PPS, will mean any system that involves the existence of or placement of a detectable infrastructure on or near a roadway that when used in conjunction with an accurate map permits a vehicle to determine its precise location. Such detectable infrastructure can comprise a MIR triad, radar reflectors, SAW devices, RFID devices, devices or marks detectable visibly such as bar codes or other recognizable objects including edges of buildings, poles, signs or the like, magnetic markers or any other object whose position is precisely known and/or is detectable in a manner that permits the vehicle to determine its position relative to the device or absolutely and where the object is noted on a map database residing within the vehicle.
If two vehicles are traveling near each other and have established communication, and assuming that each vehicle can observe at least four of the same GPS satellites, each vehicle can send the satellite identification and the time of arrival of the signal at a particular epoch to the other. Then, each vehicle can determine the relative position of the other vehicle as well as the relative clock error. As one vehicle passes a Precise Positioning Station (PPS), it knows exactly where it is and thus the second vehicle also knows exactly where it is and can correct for satellite errors. All vehicles that are in communication with the vehicle at the PPS similarly can determine their exact position and the system approaches perfection. This concept is based on the fact that the errors in the satellite signals are identical for all vehicles that are within a mile or so of each other. Furthermore, each vehicle can set its onboard clock since the vehicle passing the PPS can do so, and communicate the exact time to the others, and then each vehicle can know the carrier phase of each satellite signal at the PPS and thus invoke carrier phase DGPS.
U.S. Pat. No. 5,361,070 to McEwan, although describing a motion detector, discloses technology which is used as part of a system to permit a vehicle to precisely know where it is on the face of the earth at particular locations. The ultra wideband 200 picosecond radar pulse emitted by the low power radar device of McEwan is inherently a spread spectrum pulse which generally spans hundreds of megahertz to several gigahertz. A frequency allocation by the FCC is not relevant. Furthermore, many of these devices may be co-located without interference. The concept of this device is actually disclosed in various forms in the following related patents to McEwan. The following comments will apply to these patents as a group, all of which are incorporated herein by reference.
U.S. Pat. No. 5,510,802 to McEwan describes a time of flight radio-location system similar to what is described below. In this case, however, a single transmitter sends out a pulse, which is received by three receivers to provide sub-millimeter resolution. The range of this device is less than about 10 feet.
The concept described in McEwan""s U.S. Pat. No. 5,519,400 is that the MIR signal can be modulated with a coded sequence to permit positive identification of the sending device. In an additional McEwan patent, U.S. Pat. No. 5,589,838, a short-range radio-location system is described. Additionally, in U.S. Pat. No. 5,774,091, McEwan claims that the MIR system will operate to about 20 feet and give resolutions on the order of 0.01 inches.
g. Radar and Laser Radar Detection and Identification of Objects External to the Vehicle
A paper by Amamoto, Naohiro and Matsumoto, Koji entitled xe2x80x9cObstruction Detector By Environmental Adaptive Background Image Updatingxe2x80x9d describes a method for distinguishing between moving object pixels, stationary object pixels, and pixels that change due to illumination changes in a video image. This paper appears to handle the case of a camera fixed relative to the earth, not one mounted on a vehicle. This allows the system to distinguish between a congested area and an area where cars are moving freely. The video sampling rate was 100 milliseconds.
A paper by Doi, Ayumu, Yamamomo, Yasunori, and Butsuen, Tetsuro entitled xe2x80x9cDevelopment Of Collision Warning System and Its Collision Avoidance Effectxe2x80x9d describes a collision warning system that has twice the accuracy of conventional systems. It uses scanning laser radar. In the system described in this paper, the authors do not appear to use range gating to separate one vehicle from another.
A paper by Min, Joon, Cho, Hyung, and Choi, Jong, entitled xe2x80x9cA Learning Algorithm Using Parallel Neuron Modelxe2x80x9d describes a method of accurately categorizing vehicles based on the loop in the highway. This system uses a form of neural network, but not a back propagation neural network. This would essentially be categorizing a vehicle by its magnetic signature. Much information is lost in this system, however, due to the lack of knowledge of the vehicle""s velocity.
Work has been done at JPL (Jet Propulsion Laboratories) to develop a target recognition system. Neural networks play a key role in this target recognition process. The recognition of vehicles on a roadway is a considerably simpler process. Most of the cluttering information can be eliminated through range gating. The three-dimensional image obtained as described below will permit simple rotations of the image to artificially create a frontal view of the object being investigated. Also, the targets of interest here are considerably closer than was considered by JPL. Nevertheless, the techniques described in this reference and in the references cited by this reference, all of which are incorporated herein by reference, are applicable here in a simplified form. The JPL study achieved over a 90% success rate at 60 frames per minute.
U.S. Pat. No. 4,521,861 to Logan describes a method and apparatus for enhancing radiometric imaging and a method and apparatus for enhancing target detection through the utilization of an imaging radiometer. The radiometer, which is a passive thermal receiver, detects the reflected and emitted thermal radiation of targets. Prior to illumination, foliage will appear hot due to its high emissivity and metals will appear cold due to their low emissivities. When the target is momentarily illuminated foliage appears dark while metals appear hot. By subtracting the non-illuminated image from the illuminated image, metal targets are enhanced. The teachings of this patent thus have applicability to embodiments of the instant invention as discussed below.
U.S. Pat. No. 5,463,384 to Juds uses a plurality of infrared beams to alert a truck driver that a vehicle is in his blind spot when he begins to turn the vehicle. The system is typically activated by the vehicle""s turn signal. No attempt is made to measure exactly where the object is, only whether it is in the blind spot or not.
U.S. Pat. No. 5,467,072 to Michael relates to a phased array radar system that permits the steering of a radar beam without having to rotate antennas. Aside from that, it suffers from all the disadvantages of radar systems as described here. In particular, it is not capable of giving accurate three-dimensional measurements of an object on the roadway.
U.S. Pat. No. 5,486,832 to Hulderman employs millimeter wave radar and optical techniques to eliminate the need for a mechanical scanning system. A 35-degree arc is illuminated in the azimuth direction and 6 degrees in elevation. The reflected waves are separated into sixteen independent, simultaneously overlapping 1.8 degree beams. Each beam, therefore, covers a width of about 3 feet at 100 feet distance from the vehicle, which is far too large to form an image of the object in the field of view. As a result, it is not possible to identify the objects in the field of view. All that is known is that an object exists. Also, no attempt has been made to determine whether the object is located on the roadway or not. Therefore, this invention suffers from the limitations of other radar systems.
U.S. Pat. No. 5,530,447 to Henderson, et al. shows a system used to classify targets as threatening or non-threatening, depending on whether the target is moving relative to the ground. This system is only for vehicles in an adjacent lane and is primarily meant to protect against blind-spot type accidents. No estimation is made by the system of the position of the target vehicle or the threatening vehicle, only its relative velocity.
U.S. Pat. No. 5,576,972 to Harrison provides a good background of how neural networks are used to identify various of objects. Although not directly related to intelligent transportation systems or to accident-avoidance systems such as described herein, these techniques will be applied to embodiments of the invention described herein as discussed below.
U.S. Pat. No. 5,585,798 to Yoshioka, et al. uses a combination of a CCD camera and a laser radar unit. The invention attempts to make a judgment as to the danger of each of the many obstacles that are detected. The load on the central processor is monitored by looking at different obstacles with different frequencies depending on their danger to the present system. A similar arrangement is contemplated for embodiments of the invention as disclosed herein.
U.S. Pat. No. 5,767,953 to McEwan describes a laser tape measure for measuring distance. It is distinct from laser radars in that the width of the pulse is measured in sub-nanosecond times, whereas laser radars are typically in the microsecond range. The use of this technology in the current invention would permit a much higher scanning rate than by convention radar systems and thus provide the opportunity for obtaining an image of the obstructions on the highway. It is also less likely that multiple vehicles having the same system would interfere with each other. For example, if an area 20 feet by 5 feet were scanned with a 0.2 inch pixel size, this would give about one million pixels. If using laser radar, one pixel per microsecond is sent out, it would take one second to scan the entire area during which time the vehicle has traveled 88 feet at 60 miles an hour. On the other hand, if scanning this array at 100 feet, it would take 200 nanoseconds for the light to travel to the obstacle and back. Therefore, if a pulse is sent out every fifth of a microsecond, it will take a fifth of a second to obtain a million pixels, during which time the vehicle has traveled about 17 feet. If 250,000 pixels are used, the vehicle will only have traveled about 4 feet.
U.S. Pat. Nos. 4,352,105 and 4,298,280 to Harney describe an infrared radar system and a display system for use by aircraft. In particular, these patents describe an infrared radar system that provides high resolution, bad whether penetration, day-night operation and which can provide simultaneous range, intensity and high resolution angular information. The technology uses CO2 laser and a 10.6 micron heterodyne detection. It is a compact imaging infrared radar system that can be used with embodiments of the invention described herein. Harney applies this technology to aircraft and does not contemplate its application to collision avoidance or for other uses with automobiles.
h. Smart Highways
A paper entitled xe2x80x9cPrecursor Systems Analyses of Automated Highway Systems (Executive Summary)xe2x80x9d discloses that xe2x80x9can AHS (automated highway system) can double or triple the efficiency of today""s most congested lanes while significantly increasing safety and trip qualityxe2x80x9d.
There are one million, sixty-nine thousand, twenty-two miles of paved non-local roads in the US. Eight hundred twenty-one thousand and four miles of these are classified as xe2x80x9cruralxe2x80x9d and the remaining two hundred forty-eight thousand, eighteen miles are xe2x80x9curbanxe2x80x9d.
The existing interstate freeway system consists of approximately 50,000 miles which is 1% of the total of 3.8 million miles of roads. Freeways make up 3% of the total urban/suburban arterial mileage and carry approximately 30% of the total traffic.
In one study, dynamic route guidance systems were targeting at reducing travel time of the users by 4%. Under the system of this invention, the travel times would all be known and independent of congestion once a vehicle had entered the system. Under the current system, the dynamic delays can change measurably after a vehicle is committed to a specific route. According to the Federal Highway Administration Intelligent Transportation Systems (ITS Field Operational Test), dynamic route guidance systems have not been successful.
There are several systems presented in the Federal Highway Administration Intelligent Transportation Systems (ITS Field Operational Test) for giving traffic information to commuters, called xe2x80x9cAdvance Traveler Information Systemxe2x80x9d (ATIS). In none of these articles does it discuss the variation in travel time during rush hour for example, from one day to the next. The variability in this travel time would have to be significant to justify such a system. Naturally, a system of this type would be unnecessary in situations where embodiments of the instant invention has been deployed. The single most important cause of variability from day to day is traffic incidents such as accidents, which are eliminated or at least substantially reduced by the instant invention. One of the conclusions in a study published in the xe2x80x9cFederal Highway Administration Intelligent Transportation Systems (ITS Field Operational Test)xe2x80x9d entitled xe2x80x9cDirect Information Radio Using Experimental Communication Technologiesxe2x80x9d was that drivers did not feel that the system was a significant advance over commercial radio traffic information. They did think the system was an improvement over television traffic information and changeable message signs. The drivers surveyed on average having changed their route only one time in the eight week test period due to information they received from the system.
i. Weather and Road Condition Monitoring
A paper by Miyata, Yasuhiro and Otomo, Katsuya, Kato, Haijime, Imacho, Nobuhiro, Murata, Shigeo, entitled xe2x80x9cDevelopment of Road Icing Prediction Systemxe2x80x9d describes a method of predicting road icing conditions several hours in advance based on an optical fiber sensor laid underneath the road and the weather forecast data of that area.
There is likely a better way of determining ice on the road than described in this paper. The reflection of an infrared wave off the road varies significantly depending on whether there is ice on the road or snow, or the road is wet or dry. An unsupervised neural network could be a better solution. The system of this paper measures the road surface temperature, air temperature and solar radiation. A combination of active and passive infrared would probably be sufficient. Perhaps, a specially designed reflective surface could be used on the road surface in an area where it is not going to be affected by traffic.
What this paper shows is that if the proper algorithm is used, the actual road temperature can be predicted without the need to measure the road surface temperature. This implies that icing conditions can be predicted and the sensors would not be necessary. Perhaps, a neural network algorithm that monitors a particular section of road and compares it to the forecasted data would be all that is required. In other words, given certain meteorological data, the neural network ought to be able to determine the probability of icing. What is needed, therefore, is to pick a section of roadway and monitor that roadway with a state-owned vehicle throughout the time period when icing is likely to occur and determine if icing has occurred and compare that with the meteorological data using a neural network that is adapted for each section of road.
j. Vehicle to Vehicle Communication
U.S. Pat. No. 5,506,584 to Boles relates to a system for communication between vehicles through a transmit and transponder relationship. The patent mentions that there may be as many as 90 vehicles within one half mile of an interrogation device in a multi-lane environment, where many of them may be at the same or nearly the same range. Boles utilizes a transponder device, the coded responses which are randomized in time, and an interrogation device which processes the return signals to provide vehicle identification, speed, location and transponder status information on vehicles to an operator or for storage in memory. No mention is made of how a vehicle knows its location or how accurate that knowledge is and therefore how it can transmit that location to other vehicles.
In embodiments of the invention described herein, vehicle to vehicle communication is used, among other purposes, to allow the fact that one vehicle knows its position more accurately than another to use communication to cause the other vehicle to also improve the accuracy with which it knows its position.
Infrastructure to Vehicle Communication
The DGPS correction information can be broadcast over the radio data system (RDS) via FM transmitters for land use. A company called Differential Correction, Inc. has come up with a technique to transmit this DGPS information on the RDS channel. This technique has been used in Europe since 1994 and, in particular, Sweden has launched a nationwide DPGS service via the RDS (see, Sjoberg, Lars, xe2x80x9cA xe2x80x981 Meterxe2x80x99 Satellite Based Navigation Solutions for the Mobile Environment That Already Are Available Throughout Europexe2x80x9d). This system has the potential of providing accuracies on the premium service of between about 1 and 2 meters. A 1 meter accuracy, coupled with the carrier phase system to be described below, provides an accuracy substantially better than about 1 meter as preferred in the Road to Zero Fatalities(trademark) (RtZF(trademark)) system of this invention.
In addition to the FM RDS system, the following other systems can be used to broadcast DGPS correction data: cellular mobile phones, satellite mobile phones, MCA (multi-channel access), wireless tele-terminals, DARCs/RBDS (radio data systems/radio broadcast data system), type FM sub-carrier, exclusive wireless, and pagers. In particular, DARC type is used for vehicle information and communication systems so that its hardware can be shared. Alternately, the cellular phone system, coupled with the Internet, could be used for transmitting corrections (see, Ito, Toru and Nishiguchi, Hiroshi entitled xe2x80x9cDevelopment of DGPS using FM Sub-Carrier For ITSxe2x80x9d). Primarily, as discussed elsewhere, vehicle to vehicle communications can be used to transmit DGPS corrections from one vehicle to another whether the source is a central DGPS system or one based on PPS or other system.
One approach for the cellular system is to use the GSM mobile telephone system, which is the Europe-wide standard. This can be used for transmitting DGPS and possibly map update information (see, Hob, A., Ilg, J. and Hampel, A. entitled xe2x80x9cIntegration Potential Of Traffic Telematics).
In Choi, Jong and Kim, Hoi, xe2x80x9cAn Interim Report: Building A Wireless Internet-Based Traveler""s Information System As A Replacement Of Car Navigation Systemsxe2x80x9d, a system of showing congestion at intersections is broadcast to the vehicle through the Internet. The use of satellites is disclosed as well as VCS system.
This is another example of the use of the Internet to provide highway users with up-to-date traffic congestion information. Nowhere in this example, however, is the Internet used to transmit map information.
A paper by Sheu, Dennis, Liaw, Jeff and Oshizawa, Al, entitled xe2x80x9cA Communication System For In-Vehicle Navigation Systemxe2x80x9d provides another description of the use of the Internet for real traffic information. However, the author (unnecessarily) complicates matters by using push technology which isn""t absolutely necessary and with the belief that the Internet connection to a particular vehicle to allow all vehicles to communicate, would have to be stopped which, of course, is not the case. For example, consider the @home network where everyone on the network is connected all the time.
A paper by Rick Schuman entitled xe2x80x9cProgress Towards Implementing Interoperable DSRC Systems In North Americaxe2x80x9d describes the standards for dedicated short-range communications (DSRC). DSRC could be used for inter-vehicle communications, however, its range according to the ITS proposal to the Federal Government would be limited to about 90 meters although there have been recent proposals to extend this to about 1000 meters. Also, there may be a problem with interference from toll collection systems, etc. According to this reference, however, xe2x80x9cit is likely that any widespread deployment of intersection collision avoidance or automated highways would utilize DSRCxe2x80x9d. Ultra wide band communication systems, on the other hand, are a viable alternative to DSRC as explained below. The DSRC physical layer uses microwaves in the 902 to 928 megahertz band. However, ITS America submitted a petition to the FCC seeking to use the 5.85 to 5.925 gigahertz band for DSRC applications.
A version of CDPD, which is a commercially available mobile, wireless data network operated in the packet-switching mode, extends Internet protocol capabilities to cellular channels. This is reported on in a paper entitled xe2x80x9cIntelligent Transportation Systems (ITS) Opportunityxe2x80x9d.
According to a paper by Kelly, Robert, Povich, Doublas and Poole, Katherine entitled xe2x80x9cPetition of Intelligent Transportation Society of America for Amendment Of The Commission""s Rules to Add Intelligent Transportation Services (ITS) As A New Mobile Service With Co-Primary Status In The 5.850 to 5.925 GHzxe2x80x9d, from 1989 to 1993 police received an annual average of over 6.25 million vehicle accident reports. During this same period, the total comprehensive cost to the nation of motor vehicle accidents exceeded the annual average of 400 billion dollars. In 1987 alone, Americans lost over 2 billion hours (approximately 22,800 years) sitting in traffic jams. Each driver in Washington D.C. wastes an average of 70 hours per year idling in traffic. From 1986 to 1996, car travel has increased almost 40% which amounts to about a 3.4% increase per year.
Further, from Kelly et al., the FCC has allocated in Docket 94-124, 46.7 to 46.9 GHz and 76 to 77 GHz bands for unlicensed vehicular collision avoidance radar. The petition for DSRC calls for a range of up to about 50 meters. This would not be sufficient for the RtZF system. For example, in the case of a car passing another car at 150 kilometers per hour. Fifty meters amounts to about one second, which would be insufficient time for the passing vehicle to complete the passing and return to the safe lane. Something more in the order of about 500 meters would be more appropriate. This, however, may interfere with other uses of DSRC such as automatic toll taking, etc., thus DSRC may not be the optimum communication system for communication between vehicles. DSRC is expected to operate at a data rate of approximately 600 kbps. DSRC is expected to use channels that are six megahertz wide. It might be possible to allocate one or more of the six megahertz channels to the RtZF(trademark) system.
On DSRC Executive Roundtablexe2x80x94Meeting Summary, Appendix Ixe2x80x94Proposed Changes to FCC Regulations covering the proposed changes to the FCC regulations, it is stated that xe2x80x9c. . . DSRCS systems utilize non-voice radio techniques to transfer data over short distances between roadside and mobile units, between mobile units and between portable and mobile units to perform operations related to the improvement of traffic flow, traffic safety and other intelligent transportation service applications . . . xe2x80x9d, etc.
1. Transponders
Consider placing a requirement that all vehicles have passive transponders such as RFID tags. This could be part of the registration system for the vehicle and, in fact, could even be part of the license plate. This is somewhat disclosed in a paper by Shladover, Steven entitled xe2x80x9cCooperative Advanced Vehicle Control and Safety Systems (AVCSS)xe2x80x9d. AVCSS sensors will make it easy to detect the presence, location and identity of all other vehicles in their vicinity. Passive radio frequency transponders are disclosed. The use of differential GPS with accuracies as good as about two (2) centimeters, coupled with an inertial guidance system, is disclosed, as is the ability of vehicles to communicate their locations to other vehicles. It discloses the use of accurate maps, but not of lateral vehicle control using these maps. It is obvious from reading this paper that the author did not contemplate the safety system aspects of using accurate maps and accurate GPS. In fact, the author stresses the importance of cooperation between various government levels and agencies and the private sector in order to make AVCSS feasible. xe2x80x9cAutomotive suppliers cannot sell infrastructurexe2x80x94dependent systems to their customers until the very large majority of the infrastructure is suitable equipped.xe2x80x9d
m. Intelligent Transportation Infrastructure Benefits
A paper entitled xe2x80x9cIntelligent Transportation Infrastructure Benefits: Expected and Experiencedxe2x80x9d provides a summary of costs and benefits associated with very modest ITS implementations. Although a complete cost benefit analysis has not been conducted on the instant invention, it is evident from reading this paper that the benefits to cost ratio will be a very large number.
According to this paper, the congestion in the United States is increasing at about 9% per year. In 50 metropolitan areas, the cost in 1992 was estimated at 48 billion dollars and in Washington, D.C. it represented an annual cost of $822 per person, or $1,580 per registered vehicle. In 1993, there were 40,115 people killed and 3 million injured in traffic accidents. Sixty-one percent (61%) of all fatal accidents occurred in rural areas. This reference lists the 29 user services that make up the ITS program. It is interesting that the instant invention provides 24 of the 29 listed user services. A listing of the services and their proposed implementation with the RtZF system is:
The above references, among other things, demonstrate that there are numerous methods and future enhancements planned that will provide centimeter level accuracy to an RtZF(trademark) equipped vehicle. There are many alternative paths that can be taken but which ever one is chosen the result is clear that such accuracies are within the start of the art today.
1.3 Limitations of the Prior Art
Previous inventions have attempted to solve the collision avoidance problem for each vehicle independently of the other vehicles on the roadway. Systems that predict vehicle trajectories generally fail because two vehicles can be on a collision course and within the last 0.1 second a slight change of direction avoids the collision. This is a common occurrence that depends on the actions of the individual drivers and no collision avoidance system now in existence is believed to be able to differentiate this case from an actual collision. In the present invention, every equipped vehicle will be confined to a corridor and to a position within that corridor where the corridor depends on sub-meter accurate digital maps. Only if that vehicle deviates from the corridor will an alarm sound or the vehicle control system take over control of the vehicle sufficiently to prevent the vehicle from leaving its corridor if an accident would result from the departure from that corridor.
Additionally, no prior art system is believed to have successfully used the GPS navigational system, or an augmented DGPS to locate a vehicle on a roadway with sufficient accuracy that that information can be used to prevent the equipped vehicle from leaving the roadway or striking another similarly equipped vehicle.
Prior art systems in addition to being poor at locating potential hazards on the roadway, have not been able to ascertain whether they are in fact on the roadway or off on the side, whether they are threatening vehicles, static signs over overpasses etc. In fact, no credible attempt to date has been made to identify or categorize objects which may impact the subject vehicle.
The RtZF(trademark) system in accordance with this invention also contemplates a different kind of interrogating system. It is optionally based on scanning infrared laser radar with range gating. This system, when used in conjunction with accurate maps, will permit a precise imaging of an object on the road in front of the vehicle, for example, permitting it to be identified (using neural networks) and its location, velocity and the probability of a collision to be determined.
In particular, the system of this invention is particularly effective in eliminating accidents at intersections caused by drivers running stop signs, red stoplights and turning into oncoming traffic. There are approximately one million such accidents and they are the largest killer in older drivers who frequently get confused at intersections.
1.4 Objects and Summary of the Invention
The above and other objects and advantages of the present invention are achieved by the preferred embodiments that are summarized and described in detail below.
It is an object of the present invention to provide a new and improved method for communications involving a vehicle, including vehicle-to-vehicle communications and communications between a vehicle and a stationary object.
It is another object of the invention to utilize noise radar for automotive applications, specifically for vehicular communications.
In order to achieve objects of the invention, a method for transferring information between a vehicle and a transmitter comprises the steps of transmitting a unique pseudorandom noise signal by the transmitter in a carrier-less fashion composed of frequencies within a pre-selected band, encoding information in the noise signal relating to an identification of the transmitter and a position of the transmitter and providing the vehicle with means for extracting the information from the noise signal. The code to use for encoding the noise signal may be selected based on the position of the transmitter so that analysis of the code, or a portion thereof, provides an indication of the position of the transmitter. Information about accidents, weather conditions, road conditions, map data and traffic control devices and about errors in a GPS signal can also be encoded in the noise signals.
The information may be encoded in the noise signal in various ways, including but not limited to phase modulation of distance or time between code transmissions, phase or amplitude modulation of the code sequences, changes of the polarity of the entire code sequence or the individual code segments, or bandwidth modulation of the code sequence. The information may be encoded in the noise signal sequentially from general information to specific information about the position of the transmitter, e.g., from the country in which the transmitter is positioned to the actual square meter in which the transmitter is located.
The transmitter may be arranged in a moving object such as a vehicle to provide vehicle-to-vehicle communications, in which case, the velocity and optionally direction of travel of the vehicle is also encoded in the noise signal, or at a fixed location. In the latter case, the location can be used to correct GPS signals. In this regard, the information encoded in the noise signal may be the GPS coordinate location of the transmitter.
More particularly, in the arrangement in accordance with the invention an antenna is arranged on the vehicle to receive noise signals and a processor is coupled to the antenna. The processor may be constructed or programmed to analyze the received noise signals in order to determine whether any received noise signals originate from transmitters within a pre-determined distance from the vehicle. Such analysis can be based on an initial portion of the noise signals, i.e., the processor can scan through multiple the noise signals reading only the initial part of each to assess which noise signal(s) is/are particularly important and then obtain and process only those of interest.
Other objects and advantages of disclosed inventions include:
1. To provide a system based partially on the global positioning system (GPS) or equivalent that permits an onboard electronic system to determine the position of a vehicle with an accuracy of 1 meter or less.
2. To provide a system which permits an onboard electronic system to determine the position of the edges and/or lane boundaries of a roadway with an accuracy of 1 meter or less in the vicinity of the vehicle.
3. To provide a system which permits an onboard vehicle electronic system to determine the position of the edges and/or lane boundaries of a roadway relative to the vehicle with an accuracy of less than about 10 centimeters, one sigma.
4. To provide a system that substantially reduces the incidence of single vehicle accidents caused by the vehicle inappropriately leaving the roadway at high speed.
5. To provide a system which does not require modification to a roadway which permits high speed controlled travel of vehicles on the roadway thereby increasing the vehicle flow rate on congested roads.
6. To provide a collision avoidance system comprising a sensing system responsive to the presence of at least one other vehicle in the vicinity of the equipped vehicle and means to determine the location of the other vehicle relative to the lane boundaries of the roadway and thereby determine if the other vehicle has strayed from its proper position on the highway thereby increasing the risk of a collision, and taking appropriate action to reduce that risk.
7. To provide a means whereby vehicles near each other can communicate their position and/or their velocity to each other and thereby reduce the risk of a collision.
8. To provide a means for accurate maps of a roadway to be transmitted to a vehicle on the roadway.
9. To provide a means for weather, road condition and/or similar information can be communicated to a vehicle traveling on a roadway plus means within the vehicle for using that information to reduce the risk of an accident.
10. To provide a means and apparatus for a vehicle to precisely know its location at certain positions on a road by passing through or over an infrastructure based local subsystem thereby permitting the vehicle electronic systems to self correct for the satellite errors making the vehicle for a brief time a DGPS station and facilitate carrier phase DGPS for increased location accuracy.
11. To utilize government operated navigation aid systems such as the WAAS and LARS as well as other available or to become available systems to achieve sub-meter vehicle location accuracies.
12. To utilize the OpenGIS(trademark) map database structure so as to promote open systems for accurate maps for the RtZF(trademark) system.
13. To eliminate intersection collisions caused by a driver running a red light or stop sign.
14. To eliminate intersection collisions caused by a driver executing a turn into oncoming traffic.
Other improvements will now be obvious to those skilled in the art. The above features are meant to be illustrative and not definitive.